Production of vinyl cyanide



I alytic surface may be used, for example, a, artop of the tube onto the glass beads. The suc- Patented Nov. 12,1946

. UNi'iED STATES PATENT OFFHQE PRODUCTION or VINYL CYANIDE Charles R. Harris, Lockport, N. Y., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application January 12, 194.4,

\ SerialNo. 518,013

I '1 Claims. (Gl. 260-464) 1 2 This invention relates to the production of Example vinyl cyanide and has as its object a novel method for producing this chemical.

In accordance with my invention, I subject succinonitrlle vapor to pyrolysis at a tempera- 5 ture within the range of about 300-700 0., where-- by I have discovered that vinyl cyanide is formed in good yield by the following reaction:

A vertical stainless steel tube provided with an inlet at the top and an outlet at the bottom was arranged to be heated in an electric furnace. A layer of small porcelain Raschig rings was placed in the bottom of the tube to serve as a support for any desired layer of catalyst. Above the catalyst was placed a three-inch layer (75,

cc.) of glass beads. When no catalyst was used,

CNCECHQCN CBwHCN-I-HCN the glass beads rested on the Raschig rings. A

Th a ti i endothermi thermocouple was provided for measuring the In a preferred mode of practicing my inventemperature in the catalyst layer.

tion, succinonitrile is heated to form vapor which In operation the tube was heated to an inside is assed through a heated reactor or passed over temperature of 300 to 700 0-, and a slow stream any suitable heated surface. If desired, a catof molten succlnonitrile was introduced in the bonaceous material such as coke, charcoal or einonitrile was rapidly vaporized on contact with activated carbon, or alumina, silica gel or the the hot glass beads, d the vapors were immedilike. I have also found that alkali metal cy- 2o ately ubjected to the pyr y ng temperature. anides act as catalysts for the reaction. These The suceinenitrile vapors were i ut d with bymay be supported on granular, infusible solids drogen which was introduced in the f the such as charcoal or t other solid materials reaction tube, above the glass beads. In a series mentioned above. For this p p eI may use the runs the wing catalysts were used:

cyanides of sodium, potassium, lithium, cesium,

or rubidium, or mixtures thereof. Preferably, Run Catalyst I use a mixture of sodium and potassium cyanide containing not less than 10% of either one. Also A 300 cc. M lamine pelle s.

I prefer to carry out the pyrolysis reaction at a B 21 :gtg go fii g ge gi gi i rg d go cg temperature between the melting point of the 30 G 75 cc. of 4-8 mesh size wood charcoal impregnated with about 15% by weight of a 50-50 mixture of sodium and potassium cyanides. 12.5 cc. of the catalyst ofrun 0. it; cc. of wood charcoal, 4-8 mesh size. one.

Do. 150 cc. of the catalyst of run 0.

cyanide or cyanide mixtur and about 700 C. I have obtained my best results by using glowed wood charcoal which has been impregnated with an alkali metal cyanide.

However, excellent yields may be obtained without the use of any catalyst, especially at temperatures of 500-650 0. Some formation of The following results were obtained:

vinyl cyanide will occur when the succinonitrile is pyrolyzed at temperatures as low as 300 0., but summon. below this temperature the yield becomes too low 40 Run giff gg g iga i g fg gg 3%; to be of commercial importance. I prefer not vinylcyanide' to exceed a temperature of about 700 C. to avoid excessive, undesired decomposition reactions. era/mm. Cumin. 0. Percent I prefer to carry out the reaction intlie pres- 2 2 i;% gag 33;; ence of an inert diluent gas such as h drogen or Mg nitrogen. Such gas may be mixed with suc- 1 1:00) 525 3%, cinonitrile vapors and the vapor-gas mixture. 1,% W 8 23.2 subjected to the pyrolyzing temperature, or the 1 None 550.590 72:9 gas may be separately introduced into the reaction space. The amount of diluent gas may be 60 16mm. varied over Wide rangefrom 10% to 90% l. A process for the production of vinyl cyby Wlume the vamrgas mixture' ordmm'flyanlde which comprises subjecting succinonitrile 8' mixture o about (1111161115 8 is Preferredvapor to pyrolysis at a temperature of about 300 The followin e a p e further t ates y to 700" c. in the presence of a catalyst comprisinvention: in: an alkali metal cyanide on a solid support.

2. A process for the production or vinyl cyanide which comprises subjecting succinonitrile vapor to pyrolysis at a temperature of about 300 to 700 C. in the presence of a catalyst comprising charcoal impregnated with at least one alkali metal cyanide.

3. A process for the production of vinyl cyanide which comprises subjecting succinonitrile vapor to pyrolysis in the presence of a catalyst comprising a. carbonaceous support impregnated with at least one alkali metal cyanide at a temperature within the range of about 300 to 700 C. which is above the melting point of said cyanide.

4. A process for the production of vinyl cyanide which comprises subjecting succinonitrile vapor to pyrolysis in the presence or a catalyst comprising charcoal impregnated with a mixture of sodium and potassium cyanides at a temperature within the range or 500 to 650 C. which is above the melting point of said mixture.

'7. A process for the production of vinyl cy-' anide which comprises subjecting succinonitrile vapor together with hydrogen to pyrolysis at a temperature 01' about 500 C. to 650 C. in the presence of a catalyst comprising an alkali metal cyanide on a solid support.

CHARLES R. HARRIS. 

